The identity of the chromosomal non-histone proteins will be studied by 2 dimensional gel electrophoresis. Proteins of various nuclear sub-fractions including nuclear washes, HnRNA proteins, contractile proteins, nuclear enzymes and nuclear matrix will be identified to their moleclar weight, isoelectric point, peptide mapping, and quantitation in relation to total number of molecules per nucleus. The relationship of the various nuclear matrix proteins will be studied by peptide mapping and their distribution studied by immunofluorescent techniques. The relationship of nuclear matrix to replicating DNA will be examined by electron microscope autoradiography.